The present invention relates to a pavement (for roads), which is realized in such a way as to reduce the sound produced by vehicle traffic.
Moreover, the invention also relates to a pavement suited to collect solid or liquid pollutants which were accidentally poured thereon, so as to prevent their uncontrolled leakage in the surroundings.
These two features of the pavement, which are contained in the present invention, allow its classification in the range of so-called xe2x80x9cecotechnicalxe2x80x9d products, i.e.xe2x80x94in the present casexe2x80x94, with features reducing to a minimum the consequences for the environment due to the use of the road.
Pavements with drainage and sound absorption properties are already known in the art. A way to obtain these properties is to utilize a particular asphalt granulometry.
It has been observed that these type of pavements have high sound absorption coefficients in the high frequency range, exceeding 800-1000 Hz.
Other conventional means for sound reduction, such as acoustic barriers, vegetation and special casings for houses, have analogous sound absorption features.
However, vehicle traffic represents a source of sound which mostly contains medium-low frequencies. For this reason pavements having the feature to absorb this type of sound have also been developed, but the form of the cavities and the passage of sound waves and rain water is totally different from the present invention, and moreover, the way the pavement resists to fatigue loads due to road traffic also differs from the present invention.
An object of the present invention is to realize an ecotechnical (road) pavement and the related manufacturing process, wherein besides high frequency noise, also medium-low frequency noise is reduced.
Another object of the invention is to disconnect or separate the upper layers of the pavement from the lower ones, in such a way as to allow the high frequency sound to be absorbed by the upper layers, and the medium-low frequency sound to be absorbed through the effect produced by the separation layer acting like a Helmholtz resonator.
A further object of the present invention is to use the separation layer, besides for the absorption of medium-low frequency acoustic waves, also as an efficient
Other conventional means for sound reduction, such as acoustic barriers, vegetation and special casings for houses, have analogous sound absorption features.
However, vehicle traffic represents a source of sound which mostly contains medium-low frequencies. For this reason pavements having the feature to absorb this type of sound have also been developed, but the form of the cavities and the passage of sound waves and rain water is totally different from the present invention, and moreover, the way the pavement resists to fatigue loads due to road traffic also differs from the present invention.
U.S. Pat. No. 3,690,227 discloses a frictional, in situ self- draining structure for roadways, comprising essentially a solid imperforate and substantially impervious substrate base having a top surface adapted for the collection and channeling of liquid to a drain, and a superstratum layer, which is porous throughout its depth.
The porous superstratum layer is directly bonded to the substrate base, and the latter is inclined towards the drain conduit having a plurality of slots or holes on its upper portion.
The superstratum layer may consist only of a single layer of aggregate particles and resinous binder, or of two layers, wherein the first layer is again formed with aggregate particles and resinous binder, and the second layer comprises scoria and/or slug particles and resinous binder.
This kind of draining structure has certain features in common with the present invention.
However, it can be immediately recognized that this draining structure can only solve the problem of the rapid drainage therethrough of, e.g., rainwater, fuel oil, inflammable liquids, etc., spilled by accident or under other circumstances, on the surface of the structure.
It cannot provide for sound absorption at low frequencies, since it does not include any layer serving for that purpose, between the superstratum layer and the substrate base.
Is An object of the present invention is to realize an ecotechnical (road) pavement and the related manufacturing process, wherein besides high frequency noise, also medium-low frequency noise is reduced.
Another object of the invention is to disconnect or separate the upper layers of the pavement from the lower ones, in such a way as to allow the high frequency sound to be absorbed by the upper layers, and the medium-low frequency sound to be absorbed through the effect produced by the separation layer acting like a Helmholtz resonator.
A further object of the present invention is to use the separation layer, besides for the absorption of medium-low frequency acoustic waves, also as an efficient header for water.
Still a further object of the invention is to provide lateral reservoirs or fillings consisting of light granulated material or of another type, having selective features with respect to the absorption of different liquids, and allowing for the passage of rain water while temporarily retaining dangerous liquids, in particular pollutants which were accidentally poured on the asphalt because of accidents or other circumstances, for instance the continuos accumulation of microparticles of heavy metals, residual amounts of carbon compounds, hydrocarbon particles, etc.
Said lateral reservoirs will be associated to suitable means for draining and collecting the liquids. The lateral reservoirs are directly connected to the separation layer.
Still a further object is to use low cost materials (which therefore may form fissures) for the realization of the lower supporting layers (having different thicknesses according to the type of traffic they are designed to support) , while preventing at the same time the fissuresxe2x80x94due to fatiguexe2x80x94from ascending towards the surface, thereby causing breakage of the road upper structure; this object is attained by means of the structure and materials employed to produce the separation layer, which prevents this rise (anti-reflection cracking).